Heater not working

My air conditioner in my blows heat in the summer even if the temperasure is set for cold and cold air in the winter even if the temperature is set for heat

My car has 211000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hi there. In most cases, when the heater blows cold air, it’s due to the heater core being damaged or an obstruction of radiator coolant inside the coolant lines that heats up the core. On the reverse, when the AC does not blow cold air, it could be due to multiple problems ranging from low refrigerant to compressor failures. In this case, it’s likely that the heater / AC control switch might be the source; activating the heater in summer and AC when you need heat. You should have a professional mobile mechanic come to your location and complete a heater is not working inspection, so they can pinpoint the source of these issues you’re having and recommend the right repairs be completed.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The most common reasons a Nissan Altima heater isn`t working are a broken heater blower motor, a problem with the thermostat, or a failed heater blower motor resistor. Search our network of RepairPal Certified shops near you to speak with a technician about your issue. Oops!
Reasons Your Car Heater Is Blowing Cold Air

Heater core issues. Broken heater valve. Busted thermostat. Leaking water.

Faulty heater cores and low or contaminated coolant levels often come hand in hand, and both issues may lead to your engine overheating and your heater not blowing hot air.
If there isn`t enough coolant in your system, the heater core will blow cold air into your car. Solution: If you confirm that a low coolant level is the source of your problem, you simply need to top off your coolant. You may want to check for leaks as well if you just recently refilled your coolant.
There are a few basic issues that usually lead to the blowing of cool air from one`s car heating system: There isn`t enough coolant in the engine. There is a problem with your heater core. Your thermostats are not working correctly.
If the heater isn`t blowing hot air at you when you turn the system on, the blower fan might have a problem. Either it`s not getting electrical power or, more likely, the motor itself has simply burned out. A blower motor in an older vehicle is likely to burn out over time, and may need replacement.
A cold blowing heater can absolutely be caused by low coolant. You are on the right track. However, if that coolant is not being circulated through the heater core, the warm coolant will not cycle into the core, and the air blowing through will not warm up. You may have an issue with the thermostat or the heater core.
If your furnace is blowing cold air in your home, this is a sign of an issue with the flame detector, gas supply, air filter, pilot light, or condensate lines. Many of these issues are able to be easily solved on your own by sanitizing or replacing components in the gas furnace.
If your coolant level is a-okay, but your car heater is blowing cold air and your engine is overheating, then you have a clog in your cooling system. Conversely, if your engine temperatures are unrealistically low after a drive, your thermostat is likely the culprit.
Changing the blower fuse

If you think the cause for your car heating not working is related to the blower fuse, be sure to replace it with one of the same amperage. The fuse may have blown due to age, or it may suggest an underlying problem.

The lukewarm air appearing in your heater can be the outcome of a leaky duct. If your air ducts are leaking, cool outside air is making its way into your ductwork. This can cause the air to really feel only lukewarm. The repair: Duct sealing.
This issue happens due to a leak in either your heat pump or coil, and can be fixed by having a technician locate the leak and repair the leak. If the leak cannot be repaired, you will need to replace your AC system with a newer one. This would only be applicable if you have a heat pump system.
Replacing the heater core on a vehicle is a maintenance item that usually takes between three to eight hours to complete, depending on precisely where the heater core is located. It`s usually located under and/or behind the dashboard, requiring a great deal of time to disassemble and reassemble everything.
Your Thermostat is Stuck Open

When this component is stuck open, you may experience low engine temperature. If the engine does not warm up as it should due to a stuck open thermostat, the heater won`t be able to build up the warmth needed. The result: your car`s heater may stop blowing hot air — idle or otherwise.

Malfunctioning Throttle: A malfunctioning throttle system can cause both a high or low idle as well as an engine stall. A dirty air intake or cracked air intake tube is often the culprit. Computer Malfunction: If the powertrain control module is malfunctioning, idle speed may be affected.
A car A/C blowing hot air is often the result of a refrigerant leak. Refrigerant is a liquid that circulates through your car`s A/C system, expanding and contracting as it removes heat and humidity from the cabin. None of the other A/C components will function correctly without proper refrigerant levels.
This can happen in a closed system, or it can be due to a leak. If the system is simply low, it`s an easy fix to add refrigerant, and you can purchase and recharge it yourself at any NAPA Auto Parts store. However, if your system is leaking, you have to find and seal the leak.
This can happen in a closed system, or it can be due to a leak. If the system is simply low, it`s an easy fix to add refrigerant, and you can purchase and recharge it yourself at any NAPA Auto Parts store. However, if your system is leaking, you have to find and seal the leak.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

My dash board don’t work my front light work when I change my light into high beam and my back window won’t go down
ANSWER : As unfortunate as it is, your vehicle would be considered flood damaged. Diagnosing electrical problems in a flood damaged vehicle is nearly impossible. This would take many hours or even days to determine which wiring harnesses and circuits have been affected. Then nearly all of the wiring under the dash would likely require replacement as well as many sensors and switches. On a BMW vehicle, the amount of wires and switches are likely more than that of a lower end vehicle. Due to the inefficiency in cost, you would likely be able to purchase another BMW like yours for less than what it would cost to fix your car. Many insurance companies would consider this type of damage to total out the vehicle unfortuantely.

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Windshield wipers stopped working. They’ll suddenly stop working then suddenly start working again. Has been happening for a week.
ANSWER : The problem you are describing likely stems from an intermittent electrical fault in the wiper circuit. The windshield wiper system uses a small electric motor to move the wiper arms that you see on the windshield. That electric motor is controlled through a switch, relay, fuse, and wiring. One, or more, of those electrical components has failed although it is also possible that the mechanical arms are binding (seized, if the lubricant has dried out) thus causing the electric circuit to the motor to overload. Regardless of the underlying fault, if you request a non functioning wiper diagnostic/repair, the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Just replaced head gasket, changed crack sensor new plugs. The check engine light is on, but dim, the only other light that the dash is a normal battery indicator. The fuel pump is not running when switch is turned on, the power windows don’t work, it turns over but not firing. It’s like only one part of the system is working. Also the heater fans work even if the switch is off.
ANSWER : I would first look at the diagnostic trouble codes. Those codes are available because the check engine light is on. If the fuel pump is not running (momentarily) at key on, that fault alone will prevent the car from starting as there will be no fuel pressure. Pump output and pressure can be directly tested and you can also check for electrical power to the pump. To find out why the engine will not run, the recommended diagnostic is a no start diagnostic. If you request that service, the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.
ANSWER : It sounds like your engine might have a restriction in the cooling system. If the cooling system has a restriction that prevents its flow, this will cause the engine to get hot. The heat is dissipated from the cooling system by means of the radiator.

When a restriction exists sometimes the radiator alone is not enough. The heater core is like a small radiator inside the dash and is also another means of dissipating the heat from the cooling system. So essentially when the heat is on you are introducing a second radiator into the system which will help to cool the engine down.

In order to get this fixed, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose the overheating issue firsthand and help you make the necessary repairs.

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Heater / A/C are not working properly. They are weak and the highest and lowest settings do not work at all. Any ideas what it could be?
ANSWER : Hi there. Check the power from the switch on each setting and to the blower. See what the voltage is at each setting. If the voltage is low or not showing, then the switch is not working and needs replaced. The switch has a resister built in it to make the blower have different voltage outputs which makes the blower have multiple speeds. However, the first setting and the last setting could have a burned element inside making only the second and third setting work. Once you have the blower working properly, if there is no heat, then check the heater control valve in the engine compartment for if the vacuum line has came off or if the valve is not working. When the engine is at operating temperature, check the temperature of the coolant hoses to the valve and after the valve. If the hoses are the same temperature and the valve is shut, then the valve is on or not working. If the temperatures are different, then the valve is off or not working. If you need further assistance with your heater and a/c not working, then seek out a professional, such as one from Your Mechanic, to help you.

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My AC does not always work. If I fiddle with the blower knob I can ususally get it to work on the lowest setting.
ANSWER : Hi There,
It sounds like you may have a faulty blower motor resistor. The highest speed setting may still work because in most cars in the highest fan speed settings the current bypasses the blower motor resistor. In some cars, if the resistor is failed, the fan may stop working completely. Another reason a blower motor resistor may fail is when the blower motor has a mechanical problem or when a foreign object jams the blower motor fan blade and prevents it from spinning freely. This leads to increased current through the resistor and causes it to overheat and fail. I would suggest having an expert from YourMechanic come to your location to diagnose your system to determine what may be causing the fan not to work properly.

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All dashboard lights and tail lights do not work after driving through a lot of snow. Headlights work. And brake lights work.
ANSWER : Hello. We’ll be happy to help you. There are a few things that I recommend checking to discover why your lighting system is malfunctioning. The headlight dimmer switch should be checked. Along with the wiring harness above the right front tire behind the fender well cover. Also
the main fuse under the hood should be inspected because other people with your particular vehicle have had similar lighting issues if that fuse goes bad. It will be a great idea to check the rest of the fuses in that area too while checking the main fuse. Once the fuses are checked inside of the main fuse box then I would check the fuses inside of their interior fuse box. The interior fuse box should be located on the driver side of the dashboard near where your legs would be. If you need more assistance with repairing your vehicle please keep in mind that our organization provides Mobile Mechanics who can help you diagnose and repair your vehicle, all at competitive rates.

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Honda Civic 2008. AC stopped working suddenly and engine check light came ON for a day.Next day AC worked and no engine light.
ANSWER : Hi there. In both cases, when an AC system is not working and a warning light is coming on the dashboard, typically a professional mechanic will complete the same initial inspection, which is to download the stored error codes that triggered the warning light initially. This tends to give them an idea as to what is causing the problems. This could be something as simple as an electrical relay that is faulty or loose or an indication of a computer related "glitch". Either way, the best way to move forward is to have a professional mobile mechanic complete a check engine light inspection.

Read Full Q/A … : Heater not working